Infants receiving parenteral alimentation are subject to changing but controlled levels of exogenous carbohydrate and amino acid input, and generally receive this mode of therapy during metabolic progression from negative to positive nitrogen balance, which is frequently associated with repair of tissue insult or trauma. This situation provides a unique opportunity to study longitudinally a number of parameters important in carbohydrate/protein regulation during infusion of high glucose and constant amino acid load. This present study is designed to provide a starting point for defining control of turnover or synthesis and degradation of carbohydrate and protein within the complex metabolic clinical situations. The objectives are two-fold: 1) Assessment of the changes with time of select parameters of nitrogen metabolism, in association with 2) measurement of plasma concentrations of hormones and secondary affectors that are important in determining net carbohydrate and protein metabolism. The methodology encompasses measurements of urine and plasma samples for these parameters at selected times during the course of controlled continuous parenteral alimentation in neonates and small infants. An ultimate goal is a better understanding of the interplay of the many component units that are instrumental in determining net glucose/protein homeostasis. With this information it may be possible to design prospective modifications for improved use of this mode of therapy.